An infection is described as an invasion and growth of foreign bodies in the body.  There are four common types of infections, defined by the type of foreign invader such as bacterial, viral, parasitic or fungal.  Most serious infections in the mouth such as decay and periodontal disease are caused by bacteria.  However, fungal infections such as thrush, and viral infections such as HSV can also occur in and around the mouth. 

 

​​​​​​​​​​​​​​​​​​If a tooth cavity is left untreated then the decay can progress into the nerve of the tooth “pulp” causing the tooth to become infected by bacteria and creating an abscess.  Once the bacteria is able to penetrate the pulp, the tooth becomes irreversibly inflamed and the infection spreads from the tooth to the surrounding bone.  Once a tooth becomes infected the tooth either has to be removed or a root canal has to be performed to remove the infected nerve and bacteria from the tooth and seal it off to prevent further bacterial invasion.  In the absence of treatment a tooth infection can lead to serious medical consequences. 

 

One symptoms of a tooth infection include swelling, redness, pain and possibly exudate drainage “pus.” Sometimes the pain from a chronically infected tooth will come and go, but despite this the infection remains and will again cause pain at some point.  Most tooth pain from infection is described as continuous, relentless, gnawing, sharp, shooting or throbbing.  Other symptoms may include a foul taste or smell in the mouth, feeling ill, fever, sensitivity of the teeth to hot and cold, swelling or a bubble on the gum above or below the infected tooth, enlarged lymph nodes in the neck, extended swelling to the ear or eye.  An untreated tooth infection that spreads to other parts of the face or neck can become a life threatening medical emergency.

 

Generally a dentist can diagnose an infected tooth with an X-ray. Infected areas on the X-ray appear darker because the bacteria has destroyed this tissue making it less dense and thus darker on an X-ray. There are also some other modalities dentists may use to confirm the diagnosis of a tooth with irreversible pulpitis, the proper clinical phrase for an infected tooth. 

 

In most situations, a bacterial infection from an infected tooth will die off when the tooth is removed. This is because the tooth is the source or “loci” of the infection, and once the source of the infection is removed, the infection subsides. However, with severe infections antibiotics may be required before or after the tooth is removed to prevent the extraction from spreading to other parts of the head. In rare cases, antibiotics will be needed prior to tooth removal because it can be challenging to get a tooth numb that is severely infected. Similarly because the nerve and bacteria are removed from the tooth in a root canal, the bacteria causing the infection will die off and cease to exist.